The present invention relates to compositions for use in staining wood, and more particularly to a water-based wood stain composition available in a large variety of colors.
Ideally, a superior wood staining composition is characterized by uniformity of application in a wide range of colors and durability. Uniformity of application is affected, in part, by the rheological characteristics of the composition as well as by other factors such as the drying time of the composition. In the practical application of a stain to a wood surface, it is desirable that the stain impart a consistent color throughout the area of application. The stain should be "forgiving," i.e., in typical applications, an area of a wood surface is first coated with stain, and then an abutting second area may be stained. A common problem occurs in the area of overlap between the first area and second area wherein more color is imparted when compared to the unoverlapping areas. A "forgiving" stain is less likely to impart an area of enhanced color and thus creates a uniform color composition at the wood surface.
For commercial production purposes, a superior wood stain would, among other things, be economical, available in a large variety of colors, and consistently reproducible from batch to batch. The colors should be vibrant and clear and capable of being subject to manipulation such that they could range from transparent to opaque.
There are two basic forms of wood stains: oil-based and water-based. Oil based stains have been in long use and are capable of performing adequately in most respects. In such stains the oil base acts as a vehicle for carrying the colorant of the composition. However, more often than not, such compositions require lengthy drying times after application to a wood surface. Moreover, the Environmental Protection Agency is implementing restrictions such as the Clean Air Act of 1990 which will reduce or eventually eliminate oil-based wood stains from the market. Accordingly, the need exists for a quick-drying wood stain composition which will comply with EPA regulations.
Water-based compositions for covering wood have been proposed in the past and are available on the market. However, water-based latex paint compositions which include pigment and glycerin as components, sit on the surface of the wood, are semiopaque and tend to hide the natural grain of the wood surface. Water-based compositions including water-soluble aniline dyes as a component have also been developed. See, for example, U.S. Pat. No. 1,930,178 to Bucy and U.S. Pat. No. 1,930,178 to Mizener. However, aniline dye based stain compositions are relatively coarse and difficult to handle during application. Moreover, color matching has been extremely difficult with aniline dyes.
Finally, water-based compositions containing pigment and alkyd resins have been formulated for use as wood stains. U.S. Pat. No. 4,386,180 to Lat et al. discloses a quick-drying water-based stain for wood comprising an acrylic latex, drying oil, ester gum, glycol, hydrocarbonaceous solvent and pigment. U.S. Pat. Nos. 4,432,797 and 4,276,329 teach water-based wood stains comprising pigment and an alkyd resin to give high viscosity and prevent pigment settling. However, such compositions are characterized by either complex binding systems or slow-drying components.
Accordingly, the need still exists for a wood stain composition which complies with EPA regulations, possesses adequate transparency to enhance the natural grain of the wood, is characterized by good absorption into wood and short drying periods, and can be simply and economically formulated in a wide variety of colors.
Ease of application by the consumer is also very important. The current composition, disclosed herein, is very "forgiving" and has an open time which allows the user to cover large areas without "lapping", i.e., overlapping problems, wherein the areas that overlap evince more or different color than those that do not.